Crust:the outer layer of the earthPlate: a section of the earth's crustPlate margin: the boundary where two plates meetMantle: the dense mostly solid layer between the outer core and the crustConvection currents: the circular currents of heat in the mantleSubduction: the sinking of oceanic crust at a destructive plate marginCollision: the meeting of two plates of continental crust. They are both the same type so they meet 'head on' and buckleFold mountains: large mountain ranges where rock layers have been crumpled as they have been forced togetherOcean trenches: deep sections of the ocena, usually where an oceanic plate is sinking below a continental plateComposite volcano: a steep-sided volcano that is made up of a vairety of materials, such as lava and ashShield volcanoes: a broad volcanoe that is mostly made up of lavaSubsistence: farming to provide food and other resources for the farmer's own familyTerraces: steps cut into hillsides to create areas of flat landIrrigation: artificial watering of the landHydroelectric power: the use of flowing water to turn turbines to generate electricityNatural hazard: an occurence over which people have little control, which poses a threat to people's lives and possessions. This is different from a natural event as volcanoes can erupt in unpopulated areas without being a hazardPrimary effects: the immediate effects of the eruption, caused directly by itSecondary effects: the after-effects that occur as an indirect effect of the eruption on a longer timescaleAid: money, food, training and technology given by richer countries to help poorer ones, either to help with an emergency or to encourage long-term development Earthquake: a sudden and often violent shift in the rocks forming the earth's crust, which is felt at the surfaceImmediate responses: how people react as the diaster happens and in the immediate aftermathLong-term responses: later reactions that occur in the weeks, months and years after the eventVent: the opening - usually central and single - in a volcano from which magma is emittedLahar: these secondary effects of a volcanic eruption are mudflows resulting from ash mixing with melting ice or waterSupervolcano: a mega colossal volcano that erupts at least 1,000km cubed of ashCaldera: the depression of the supervolcano marking the collapsed magma chamberfissures: extended openings along a line of weakness that allow magma to escapeGeothermal: water that is heated beneath the ground, which comes to the surface in a variety of waysGeyser: a geothermal feature in which water erupts into the air under pressureHot spot: a section of the earth's crust where plumes of magma rise, weakening the crust, These are away from plate boundariesFocus: the point in the earth's crust where the earthquake originatesRichter scale: a logarithmic scale used for measuring earthquakes, based on scientific recordings of the amount of movementEpicentre: the point at the earth's surface directly above the focusShock waves: seismic waves generated by an earthquake that pass through the earth's crustMercalli scale: a means of measuring earthquakes by describing and comparing the damage done, on a scale of I to XIIDebt: money owed to other, to a bank or to a global organisation such as the world bankThe three Ps: the collective term for prediction, protection and preparationPrediction: attempts to forecast an event - where and when it will happen - based upon current knowledgeProtection: constructing buildings so that they are safe to live in and will not collapsePreparation: organising activities and drills so that people know what to do in the event of an earthquakeTsunami: a special type of wave where the entire depth of the sea or ocean is set in motion by an event, often an earthquake, which displaces the water above it and creates a huge wave
